Error! Unable to detrmine page link

I suddenly get this error when i try to access "catalog - Categories/products" screen

[B]Error!

Unable to determine the page link!

Function used:

zen_href_link('', 'cPath=&product_type=&pID=&action=delete_product', 'NONSSL')[/B]

What's causing it?

I've tried clearing cache and switching off SEO URLs but that doesn't resolve the problem.

What version of Zen Cart?
And what addons/contributions do you have installed?

I'm using zencart 1.3.7 and i have imagehover, superorders installed.

The last thing i installed was multiple shipping tables module which comes with Zencart by default and i'm prompted to just install.

Would that cause a problem? As the shipping table has not been configured to anything

This is the full message i get

--- Z:\Downloads\ZenCart\zen-cart-v1.3.5-full-fileset-09032006\zen-cart-v1.3.5-full-fileset-09032006\admin\includes\modules\category_product_listing.php Tue Mar 14 00:27:34 2006 +++ Z:\Downloads\ZenCart\image-handler_2.0-zc13\image-handler_2.0-zc13\admin\includes\modules\category_product_listing.php Mon May 01 15:46:02 2006 @@ -4,7 +4,7 @@ * @copyright Copyright 2003-2006 Zen Cart Development Team * @copyright Portions Copyright 2003 osCommerce * @license http://www.zen-cart.com/license/2_0.txt GNU Public License V2.0 - * @version $Id: category_product_listing.php 3182 2006-03-14 04:27:33Z ajeh $ + * @version $Id: category_product_listing.php,v 1.1 2006/04/14 13:42:13 tim Exp $ */ if (!defined('IS_ADMIN_FLAG')) { die('Illegal Access'); @@ -324,6 +324,7 @@

Error!

**Unable to determine the page link!

Function used:

zen_href_link('', 'cPath=&product_type=&pID=&action=delete_product', 'NONSSL')**